Data is a vital aspect of testing that we do, be it functional tests or unit tests. However, a lot of times in software development the data is “estimated” and not necessarily well defined. Eventually when going to deployment and the existing data which needs to be migrated is about to be transferred, the team discovered to the horror that the data is slightly different – this could range from missing data to repeating of key columns. As a result last minute modifications are made and minimally tested before being deployed and hoping for the best.

So if it works, that’s great! But an earlier test deployment generally helps avoid this risk, or delaying the release until the data is ready (the system can’t be used if there is no data after all).